Ball Screw replacement for wearing thread nuts

That looks a really neat job.

My ball nuts arrived today, so now it's the mounting adapters to machine out of aluminium. The Stepcraft will have its first run on aluminium doing these, so any guidance on feeds, speeds, cut depth and lubrication would be very welcome.

Incidentally, could you please let me know the shank size of the old nut - I've guessed at 10mm to take the M6 screw. I don't want to disable/dismantle my machine until the upgrade kit of bits is complete.

I was at an Engineering Exhibition today and learned that CNC4YOU are integrating a wireless control pendant into UCCNC (V1.3xxx?). It will be available in a few weeks once the final bugs are ironed out and testing is completed - so they say.

Thanks,

Peter.

Incidentally, could you please let me know the shank size of the old nut - I've guessed at 10mm to take the M6 screw.

Just measured 10.95mm

Finch, where did you order the nylon connector?

Proto,

Thanks so much for that - I can complete the CAD now.

Peter

That looks a really neat job.

I was at an Engineering Exhibition today and learned that CNC4YOU are integrating a wireless control pendant into UCCNC (V1.3xxx?). It will be available in a few weeks once the final bugs are ironed out and testing is completed - so they say.

Thanks,

Peter.

I have the wireless XHC-HB04 running with UCCNC 2.26 here. The plugin seems to have some bugs (you have to disable the pendant for probing, but can be done with a modified probing macro), but it is really cool to use.
Only around 100 Euros on ebay: http://www.ebay.de/itm/Wireless-Handwheel-CNC-Fraser-Elektronisches-Handrad-Encoder-for-Mach3-3-4-Achse-/272319627895?hash=item3f6783c277:g:ql0AAOSwmLlX-E86

Magnus

Ever since we switched over to the UC400 Ethernet, the machine had not missed a beat. Wireless allways has the potential for disaster, a little bit of interference on a 10 hour job and walla.chaos

Hmm.

This all seems to be moving along apace.

I don't know whether the original Stepcraft screw is a leadscrew or ballscrew but the helical channel certainly looks like it will accept ball bearings o.k.

I wasn't sure what the difference is but this link explains it. You can download an engineer's guide PDF but you will have to provide some contact details.

http://blog.helixlinear.com/bid/224687/Lead-Screws-vs-Ball-Screws-It-s-All-about-the-Application

Doug

Doug,

I've assumed (and I hope I am correct!!!) that the original screws are in fact ball screws, since one enterprising user has already prepared the way.

Here is his original picture on what he implies is the original screw - it all looks genuine to me. I'm ordering a new Z screw from Rory anyway (my original has some runout that I partially corrected with shims) so I'll have a definite answer fairly soon.

Looking at the picture that Finch posted, it looks as though he is opting for 8mm screws and nuts rather than the original 10mm. I guess this avoids having to mill a 1mm deep recess to accommodate 21mm diameter of the ballnut.

Hmm...... dunno, I'll need to check what my mate ordered again, but I thought it was the same, our nut diam is 19mm so no recess needed

Hi Peter.

Yes, I assume and hope it's a ballscrew too. 🙂 That mod looks clever; I hope that you can reproduce it.

The Zapp Automation price of £43 is ideal; £160-£170 region to replace all four is o.k. but I'm too new to this to start modifying my machine before I've even cut a piece. I read on that link that ballnuts are not ideal for vertical applications..,

I'll keep this in mind for future work after I've done a lot of cutting and can justify a strip down and rebuild.

Great stuff guys 🙂

Doug

Hi Doug,

I think the problem with vertical axes is that because of the low friction, a heavy assembly could back drive the ball screw and let the whole lot descend gracefully (or not as the case may be!!) to the base plate or whatever it hits first.

With a stepper motor drive, hopefully there is enough residual magnetism to keep things in check - I've tried mine with it unpowered and one can definitely feel the poles. A case of suck it and see - not a problem once it's recognized.

Peter.

Afraid the news is not very encouraging - the Zapp Automation ball nut doesn't match the standard ball/lead screw!! At least 1/4mm backlash and an altogether poor fit.

Assembled and dis-assembled the setup a few times to try to what was going wrong, and at the last time a couple of balls dropped out - so now I have the unenviable task if getting them back!! Going to have to make a jig to do that as the GTEN design is very non-standard (and novel) as far as I can tell. Three individual return paths, one from each of three threads if I understand the construction correctly.

Ball diameters are 1.71mm, and the Stepcraft screw looks to be able to accommodate nearer 2mm (cant measure this exactly). I can only conclude that the Eichenberger ball nut uses a larger size since the original experimenter reported little or no backlash.

I am wondering whether to risk £90 on one of the Eichenberger ball nuts !!! Motivation not high at the moment!!

Peter.

I hate to say I told you so. Just buy the matching precision thread from ZAP automation and be done with it - if you want it to work

Afraid the news is not very encouraging....

I am wondering whether to risk £90 on one of the Eichenberger ball nuts !!! Motivation not high at the moment!!

Peter.

Really sorry to hear that. I probably would have stuck with the Eichenberger since it appears those worked, and then only tried 1 axis to verify it. It sucks taking a risk like that, plus all the work to change the part.

Were you able to make the adapter ok? I'd still like to know if the Eichenberger ball nuts will work but don't have the resources to try it myself right now. Let us know if you decide to try.

Hi Proto,

I think I might have a chat to the sales manager at Moore - might be able to either get hold of an externally damaged Eichenberger ball nut or persuade him to try my Z ball screw in one on his premises. Nothing ventured etc!!

I did get as far as partially machining a mounting adapter - it needs the mounting spigot turning and tapping once the height of the ball screw centre is determined. Easy to do in a 4 jaw chuck on my lathe. The M18 x 1 thread was much easier than I thought - a taper tap in aluminium worked wonders!!

GTEN ball nut and part finished adapter.